WO2023282216A1 - Concrete pouring method - Google Patents

Abstract

In the present invention, when pouring concrete into a mold, a coarse aggregate is evenly distributed in the mold by a simple method. The concrete is poured by filling a mold (test body creation container 20) in advance with a metal coarse aggregate 10A that is bulkier than gravel and has a rigidity with which the metal coarse aggregate does not deform under its own weight, and filling the mold with mortar 30 while applying a vibration thereto. It is preferable that vibrations are initially applied to the metal coarse aggregate that fills the mold, and then the mortar is filled into the mold while applying vibrations to the mortar.

Description

Concrete placement method

The present invention relates to a concrete placing method.

Concrete is usually made by mixing cement, water, coarse aggregate (crushed stone and gravel) and fine aggregate (sand), so-called ready-mixed concrete, and solidifying it based on the hydration reaction between water and cement. It is widely used as a building material.

Concrete has the disadvantage that its tensile strength is very low at about 1/10 to 1/13 compared to its compressive strength. In order to compensate for this drawback, it is common to arrange reinforcing bars in a matrix in the concrete, but as a new coarse aggregate that can improve not only compressive strength but also tensile strength, metal A roughly tetrahedral coarse aggregate has been proposed (Patent Document 1). Since this coarse aggregate exhibits an anchoring effect in mortar due to its substantially tetrahedral outer shape, it is possible to improve tensile strength and shear strength compared to conventional coarse aggregate.

In addition, in order to improve the adhesion between the metal coarse aggregate and mortar, the coarse aggregate is made by passing a thin wire of No. 20 or more through the metal coarse aggregate body. A wire has been proposed in which a wire can be easily wound (Patent Document 2). According to this coarse aggregate, the wire is wound around the main body of the coarse aggregate during stirring of the ready-mixed concrete. It is difficult to settle, and the dispersibility of coarse aggregate is improved.

However, in the metal coarse aggregate as described in Patent Document 1, the tensile strength of the coarse aggregate itself is too strong compared to the strength of the concrete mortar portion, so the interface between the coarse aggregate and mortar may separate and break the mortar part, and the coarse aggregate may not contribute to improving the tensile strength of concrete.

As described in Patent Document 2, if the wire is wound around the metal coarse aggregate body, the adhesion between the coarse aggregate and mortar can be improved. Since the way of winding is not constant, there is a possibility that the tensile strength may vary.

On the other hand, in order to further improve the adhesion between mortar and coarse aggregate, prevent breakage of the mortar part, and improve the tensile strength of concrete, coarse aggregate made by molding metal mesh material into hollow spheres is used. It has been proposed (Patent Document 3).

On the other hand, as a concrete casting method, water, cement, sand, and coarse aggregate are mixed in advance in a mixer to prepare ready-mixed concrete, which is then poured into a formwork and compacted using a vibrator. is done.

Japanese Patent No. 6485932 Japanese Patent No. 6532073 Japanese Patent No. 6667886

Conventionally, gravel, which has been widely used as coarse aggregate, is easy to separate from mortar in ready-mixed concrete. As a result, there is concern that the gravel will be unevenly distributed within the formwork and that the strength of the concrete will become uneven.

On the other hand, when the metal coarse aggregates described in Patent Documents 1, 2, 3, etc. are used, the metal coarse aggregates are bulkier than gravel, and the adhesion of mortar is also improved. well dispersed in the mortar.

However, it is difficult to evenly fill the mold with a predetermined amount of coarse aggregate while the coarse aggregate is dispersed in mortar.

On the other hand, the object of the present invention is to enable a predetermined amount of coarse aggregate to be driven into the formwork with a simple method and with as little labor as possible.

In order to solve the above-mentioned problems, the inventor of the present invention previously filled the formwork with coarse metal aggregate that is bulkier than gravel and has rigidity that does not deform under its own weight, and then poured mortar into the formwork while vibrating it. A method of placing concrete for filling is provided.

Here, the metal coarse aggregate is bulkier than gravel, for example, a compressive strength test (JIS A 1108 concrete compressive strength test method) or a tensile strength test (JIS A 1113 concrete splitting tensile strength test method) The weight of gravel in a cylindrical container with an inner diameter of 10 cm and a depth of 20 cm is about 2.5 kg. In particular, it means 1 kg or less.

According to the method of the present invention, the formwork is filled with coarse metal aggregate that is bulkier than gravel, and then the formwork is filled with mortar while being vibrated. can be filled into the formwork.

Next, when the mortar is filled while vibrating, the mortar can enter the gaps in the bulky coarse aggregates and the gaps between the coarse aggregates. Even if the vibration is continued, the mortar does not enter the form any more, and the concrete is compacted. In this way, a mixer is not required, and concrete can be placed easily in terms of equipment and labor.

FIG. 1A is a perspective view of a coarse metal aggregate 10A that can be used in the present invention. FIG. 1B is a perspective view of a coarse metal aggregate 10B that can be used in the present invention. FIG. 1C is a perspective view of a coarse metal aggregate 10C that can be used in the present invention. FIG. 1D is a perspective view of a coarse metal aggregate 10D that can be used in the present invention. FIG. 1E is a perspective view of a coarse metal aggregate 10E that can be used in the present invention. FIG. 1F is a perspective view of a coarse metal aggregate 10F that can be used in the present invention. FIG. 1G is a perspective view of a coarse metal aggregate 10G that can be used in the present invention. FIG. 1H is a perspective view of a coarse metal aggregate 10H that can be used in the present invention. FIG. 2A is an explanatory diagram of a method for fabricating a specimen. FIG. 2B is an explanatory diagram of a method for producing a specimen. FIG. 2C is an explanatory diagram of a method for fabricating a specimen. FIG. 2D is an explanatory diagram of a method for fabricating a specimen.

　Hereinafter, the casting method of the present invention will be described in detail with reference to the drawings. In each figure, the same reference numerals denote the same or equivalent components.

(Overview of pouring method)
The method of placing concrete according to the present invention is roughly a method in which coarse metal aggregates are preliminarily filled into a formwork, and then mortar is filled into the formwork while being vibrated.

(Metal coarse aggregate)
The coarse metal aggregate used in the present invention is bulkier than gravel and has a rigidity that does not deform under its own weight. Here, the fact that the metal coarse aggregate is bulkier than the gravel means that the weight when filled in a container of a predetermined capacity is lighter than the gravel, as described above.

Examples of such coarse aggregates include metal coarse aggregates described in Patent Documents 1, 2, and 3, wire coarse aggregates described in Japanese Patent Application No. 2022-28649, and Japanese Patent Application No. 2022-89107. Coarse aggregates made of metal strips described above, coarse aggregates formed from floor nail-like wires, and the like can be used.
Metal coarse aggregate 10A shown in FIG. 1A, for example, can be mentioned as a metal coarse aggregate that can be produced by a forming machine, which is excellent in mass productivity and can be obtained at low cost. This coarse aggregate 10A is made of a single wire 1, has a spiral portion, and has a rigidity that does not deform under its own weight.

Alternatively, as shown in FIG. 1B, a metal coarse aggregate 10B having two curved helical axes may be used. The coarse aggregate 10B is made to have a diameter of less than 30 mm. The metal coarse aggregate 10C shown in FIG. 1C has two curved spiral axes like the coarse aggregate 10B shown in FIG. 1B, but the diameter of the coarse aggregate is about 30 to 40 mm. . It is also preferable to have one circular spiral axis like the coarse aggregate 10D shown in FIG. 1D and the coarse aggregate 10E shown in FIG. 1E. Each of these coarse aggregates 10A, 10B, 10C, 10D, and 10E is bulky by having a helical portion in which the wire 1 is wound with a gap. Moreover, it is preferable that the helical surface is twisted like the coarse aggregate 10F shown in FIG. 1F. According to these coarse aggregates, when a plurality of coarse aggregates are accumulated, the coarse aggregates are entangled with each other, the tensile strength of the concrete is increased, the concrete exhibits stickiness against excessive loads, and the explosion is prevented. be.

A coarse aggregate 10G shown in FIG. 1G, which is formed of strip-shaped metal strips, can also be preferably used. In this coarse aggregate 10G, both ends of the band-shaped piece 2 are branched, the branched portions are separated from each other, and the surfaces of both ends formed by the branched portions are in twisted positions. Therefore, when a plurality of coarse aggregates 10G are accumulated, the coarse aggregates 10G are not densely overlapped, and there are gaps between the coarse aggregates 10G, resulting in bulkiness. In addition, since the branched portions at the ends of the coarse aggregate 10G are separated from each other, when a plurality of coarse aggregates are accumulated, the branched portions of the accumulated coarse aggregates are entangled with each other, and the tensile strength of the concrete is reduced. It increases, exhibits tenacity against excessive loads, and prevents explosions.

Thus, in the present invention, the metal coarse aggregates are rigid enough not to be deformed by their own weight, and are formed of wire or strip-shaped metal, and do not overlap each other exactly by having loops or curved portions, Metal coarse aggregates of various shapes that are bulky and accumulated can be preferably used. In particular, if the axis of the helical portion of the metal coarse aggregate is curved or the surface formed by the loops or curved portions is twisted, a plurality of metal coarse aggregates will be entangled with each other due to the excitation. things are preferred.

In addition, in the present invention, a metal mesh 3 formed into a sphere (Patent Document 3) can also be preferably used, like the coarse aggregate 10H shown in FIG. 1H. This coarse aggregate 10H is bulky, and mortar enters into the spherical coarse aggregate 10H, which is preferable in that the coarse aggregate 10H and the mortar are easily integrated.

In the method of the present invention, there is no step of pumping ready-mixed concrete in which coarse aggregate is dispersed. However, from the viewpoint of ease of handling, it is preferable that the maximum diameter of the coarse aggregate is approximately the same as that of gravel or crushed stone, which are conventional coarse aggregates. Specifically, it is preferable to set the maximum diameter of the coarse aggregate to the particle size and particle size range specified in JIS A 5005 and JIS A 5308.

(wire)
When the coarse aggregate used in the present invention is made of wire, various types of iron wire, steel wire and the like can be used as the wire. A spring material such as a piano wire or a hard steel wire may be used, a less expensive soft steel wire may be used, or a copper wire or the like may be used. Further, it is preferable to use a magnetic material such as an iron wire as the wire, because the magnet can be used in the transportation process of the coarse aggregate and concrete products using it. On the other hand, the use of steel wire is preferable in that the strength of the coarse aggregate itself increases and the strength of the concrete also increases.

As the wire, a stranded wire obtained by twisting multiple wires or a wire with an irregular cross section may be used. As a result, the bond between the wire and the mortar portion can be strengthened and the strength of the concrete can be improved.

The wire diameter of the wire can be appropriately set according to the shape of the coarse aggregate, but is preferably 0.5 mm to 6 mm, more preferably 1 mm to 3 mm, and even more preferably 1 mm to 2 mm in terms of handleability.

(mortar)
The type of mortar used in the present invention is not particularly limited. It can be formed from common Portland cement, sand and water. No admixtures or special fibers used in making high-strength concrete are required.

Also, as the sand, it is possible to use recycled concrete sand formed from recycled concrete. By using the above-described metal coarse aggregate in the present invention, even when using recycled concrete sand, it is possible to exhibit the same concrete strength as when using general sand.

(Placement method)
As a casting method, first, coarse aggregate is filled in the mold, and then mortar is filled in the mold while being vibrated. In this case, the coarse aggregate can be filled on top of the waste concrete in the mold. Also, the mortar can be poured over the coarse aggregate. It is not necessary to insert a tremie tube inside the packed bed of coarse aggregate and use the tremie tube to force mortar into the packed bed of coarse aggregate.

　Before filling with mortar, it is preferable to vibrate the coarse aggregates in the form first, and to entangle the coarse aggregates as much as possible. In this case, it is preferable to vibrate the upper surface of the coarse aggregate filled in the mold with a vibrator so that the vibration spreads over the entire coarse aggregate in the mold. A vibrator may be used to vibrate the bottom of the formwork from outside the formwork. Also, if necessary, a vibrator may be inserted into the mortar to vibrate it.

Next, fill the mortar while vibrating. It is preferable to divide the filling of the mortar into a plurality of times and to continue the vibration between each filling. Vibration causes the mortar to enter the gaps between individual coarse aggregates and the gaps between coarse aggregates. In addition, the coarse aggregates are entangled with each other due to the excitation, and the strength of the concrete is improved.

(Application example of coarse aggregate)
Various concrete precast products can be mentioned as application examples of the concrete placing method of the present invention. It is also preferably applicable to concrete structures that do not use reinforcing bars (eg, dam walls, roads laid directly on the ground, mat foundations of buildings, paved open spaces, etc.). As a special application example, it can be preferably applied to a reinforced concrete floor slab of a highway, which is installed at a position away from the ground. When coarse aggregate made of a magnetic material is used, the concrete panel can be attracted to an electromagnet for transportation, installation, and removal, improving workability.

Hereinafter, the effects of the coarse aggregate of the present invention will be specifically described using experimental examples.
Experimental examples 1-7
<Preparation of specimen>
A sample-producing container serving as a sample-type is a cylindrical container with an inner diameter of 10 cm and a depth of 20 cm. Using this container, a specimen was produced as follows.
First, mortar was made by mixing cement, sand and water according to the following formulation.
water:cement:sand=0.55:3:3

(Example installation method: A)
Using the mortar described above, a specimen was produced by the method of the example as shown in FIGS. 2A to 2C. That is, the sample-preparing container 20 is filled with the coarse aggregate 10 in such an amount as to fill the container 20 (FIG. 2A). The above-described mortar 30 was poured onto the coarse aggregate 10 filled in the specimen-preparing container 20 (FIG. 2B). Since the mortar 30 piled on the coarse aggregate 10 permeates into the container 20 due to vibration, the shape of the coarse aggregate 10 appears near the opening of the container 20 (Fig. 2C). Therefore, the mortar 30 is piled up again on the coarse aggregate 10 and penetrated inside. This is repeated until the mortar 30 does not permeate the inside of the container, and then the surface of the mortar 30 is smoothed (Fig. 2D). In this way, the container 20 was filled with the mortar 30 without gaps. This was hardened by aging it in water for 28 days, and the hardened product was removed from the container and used as a test piece.

(Casting method of comparative example: B)
As a comparative test, a coarse aggregate was added to the above mortar and stirred, and an appropriate amount of the obtained mixture was filled in a container and the container was shaken. Filling the container and shaking were repeated. During this time, the mortar overflows from the container, and some of the coarse aggregate also overflows from the container. was filled in the container.

The unhardened concrete filled in the container was hardened by curing in water for 28 days, and the hardened material was removed from the container and used as a test piece.

In addition, gravel was used as the coarse aggregate, and the casting method of the comparative example was performed in the same manner as described above to prepare a specimen.

<Evaluation>
A compressive strength test (JIS A 1108 Concrete Compressive Strength Test Method) and a tensile strength test (JIS A 1113 Concrete Splitting Tensile Strength Test Method) were performed on each of them. Compressive strength tests and tensile strength tests were conducted at the General Incorporated Foundation Testing Center for Construction Materials. Table 1 shows the results.

In Table 1, a comparison of Experimental Examples 2 and 3, a comparison of Experimental Examples 4 and 5, and a comparison of Experimental Examples 6 and 7 reveals that the placing method of the Example has higher compressive strength and strength than the placing method of the Comparative Example. Although the tensile strength is slightly low, it is remarkably superior in tensile strength in comparison with the gravel used as coarse aggregate in Experimental Example 1, and has excellent strength as concrete.

According to the casting method of the embodiment, since it is not necessary to mix coarse aggregate and mortar in advance using a mixer, concrete can be cast simply and at low cost in terms of equipment and labor. I understand.

1 Wire 2 Strip 3 Metal mesh 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H Coarse aggregate 20 Specimen preparation container 21 Setting table 30 Mortar

Claims (6)

A method of placing concrete in which rough metal aggregate, which is bulkier than gravel and has rigidity that does not deform under its own weight, is filled in advance in the formwork, and mortar is filled in the formwork while being vibrated. The placing method according to claim 1, wherein the metal coarse aggregate in the formwork is vibrated before filling the formwork filled with metal coarse aggregate with mortar. The placing method according to claim 1 or 2, wherein the upper surface of the metal coarse aggregate filled in the formwork is vibrated by a vibrator. The placing method according to claim 1 or 2, wherein the bottom of the formwork is vibrated from outside the formwork with a vibrator. The placing method according to claim 1 or 2, wherein the coarse metal aggregate is formed of wire, and the wire has a rigid loop or curved portion that does not deform under its own weight. The coarse metal aggregate is formed of strip-shaped metal pieces, and at least one end of the strip-shaped metal pieces is branched into small pieces by slits in the longitudinal direction of the metal pieces, and the branched portions are spaced apart from each other. The placing method according to claim 1 or 2.

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